In the RAR file you'll find a data folder and 4 vpks.
Place the data folder in ux0:/ and if you want to play Full game or Spear of Destiny (SoD) full game, you'll need to place wl6 and sod files in ux0:/data/Wolfenstein 3D. Shareware version and Spear of Destiny Demo files are already included in the data folder.​

According to what version you want to play, install the relative vpk file. (You can also install more than a single vpk).​